Simply put, a gun that looks like a fish.

Used by firearms enthusiasts and Keyboard Kommandos to mock designs perceived to have too many polymer parts, or be too organic in shape.

Common examples include the XM8 and the FN F2000, both of which possess the distinctly fishy outline which lends the term its name.
Burt: "Hey, Cletus! I got me one 'o them neewfangled Eff two thousand guns from waffle land!"

Cletus: "Fuck you Burt, you stupid mall ninja, that's a damn fishgun!"
by XxxAnalInfiltratoRxxX July 9, 2014
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